Typically within a motor vehicle there is provided a ventilation system through which air flows can be directed towards occupants of that vehicle. These air flows may be chilled or heated as required by the occupants. In broad terms, it is normal for such ventilation systems to present air flows at respective heights directed towards the occupants of the vehicle. Such systems are termed bi-level and present respective air flows to occupant torso and foot areas.
Provision of automatic adjustments for the climate within a motor vehicle is becoming common. Thus, air conditioning systems will heat or cool air projected into the motor vehicle cabin in order to adapt the climate therein. Furthermore, air conditioning systems can act as dehumidifiers in order to inhibit misting of windows, etc. Such automatic climate control systems compare actual vehicle cabin temperature with desired vehicle cabin temperature in relation to current ambient temperature about the vehicle and other information indicative of environmental conditions. Thus, in most automatic climate control systems, when in automatic mode, air flow distribution between projection heights is varied in accordance with a predetermined target air outlet (TAO) relation which considers the previously mentioned parameters.
Inherently, most users, i.e. the occupants of the motor vehicle, have individual preferences for respective air flow rates and distributions which cannot be accommodated through generalised predetermined relations identified by the motor vehicle manufacturer. Thus, the automatic climate control system will include a manual override to allow that occupant of the motor vehicle to select their individual preferences for air flow rates and distribution in accordance with current conditions and mood.
Unfortunately, such manual selection of air distribution and flow rates typically provides for a simple fixed proportion ratio level between air flow projection vent heights. Thus, in a bi-level system there will be fixed 50/50 air flow mix between a head height and a foot height directed towards occupants of a motor vehicle. Such fixed split is acceptable during mild conditions such as prevalent during Spring and Autumn. However, in more extreme conditions, prevalent in Winter or Summer, this fixed split may be unacceptable or, at least, be significantly different from that expected by the occupant. In such circumstances, in Winter there is too much air flow towards the face whilst too little towards the feet, whilst in Summer air flow to the face is insufficient for comfort. Thus, an uncomfortable occupant of a motor vehicle will tend to constantly change the temperature control arrangement settings in order to achieve a comfortable condition. Such repetitive alteration in the climate control system will typically diminish overall efficiency of that system along with creating potentially unsafe and irritable driving conditions for the occupant of the vehicle.